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Growth changes and characteristics of cadmium accumulation and distribution in Pistia stratiotes under cadmium stress
Received:January 04, 2022  
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KeyWord:cadmium;Pistia stratiotes;subcellular distribution;chemical form
Author NameAffiliationE-mail
HUANG Rui College of Landscape Architecture, Nanjing Forestry University, Nanjing 210037, China  
XIN Jianpan College of Landscape Architecture, Nanjing Forestry University, Nanjing 210037, China  
TIAN Runan College of Landscape Architecture, Nanjing Forestry University, Nanjing 210037, China tianrunan@njfu.edu.cn 
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Abstract:
      Pistia stratiotes plants were treated with different cadmium concentrations(0, 10, 25, 50, 75 μmol·L-1, and 100 μmol·L-1)in a nutrient solution for 18 days to explore the effects of cadmium stress on the growth and cadmium accumulation and distribution characteristics of P. stratiotes. The biomass, growth form, and cadmium content were determined, and the subcellular distribution and chemical forms of cadmium in leaves were analyzed. The results showed that as the cadmium concentration increased, the biomass, canopy diameter, leaf and tillering number, and cadmium bioconcentration factor gradually decreased. The overground cadmium content and cadmium transfer coefficient increased, while the underground and total cadmium content as well as the number of individual plants first increased and then decreased. The cadmium content underground was higher than that overground under each treatment. When the cadmium concentration >10 μmol·L-1, the cadmium content of the cell wall was the highest(42.61%~46.91%), followed by that in the organelles(27.04%~39.72%) and soluble(17.68%~26.06%) in leaves. The cadmium ratios in the cell wall and soluble increased gradually with the increase of cadmium concentration; however, those in the organelles showed a downward trend. Cadmium was mainly extracted by acetic acid(35.00%~59.06%), followed by sodium chloride(16.72%~26.45%)and water(7.77%~33.22%)in leaves. In conclusion, P. stratiotes avoided serious cadmium stress damage through root fixation, cell wall fixation, and vacuolar compartmentalization, and reduced cadmium toxicity and mobility through acetic acid extraction state storage. After 10~100 μmol·L-1 cadmium treatment for 18 days, P. stratiotes could maintain higher cadmium enrichment and lower biomass to avoid secondary pollution caused by their rapid growth during the ecological restoration of cadmium-polluted waters.